While the idea of a small file size is tempting, there are a few trade-offs to keep in mind.
"Highly compressed" refers to files (usually in .rar, .zip, or .7z formats) that have been shrunk down using advanced compression algorithms. The goal is to make a 20GB game fit into a 5GB or 10GB package, making it easier to download for users with slow or data-limited internet. Gta V Ps3 Highly Compressed